Emergency — phone the vet now Within 2 hours for best outcome

Dog bitten by a UK adder

Carry the dog to the car — do not let them walk — and head to the vet now; antivenom works best within hours.

Dog

Recognise the signs

Sudden yelp from undergrowth on a walk
Two small puncture marks, often on the muzzle, face, neck, or front legs
Rapid, marked swelling at the bite site within minutes
Bruising spreading from the bite
Pain, lameness, reluctance to move
Drooling, vomiting, weakness
Pale gums, fast breathing, collapse in severe cases

First aid steps

Carry the dog to the car if at all possible — walking pumps venom around the body.
Phone the vet en route to confirm they hold antivenom or know which nearby practice does.
Note the time of the bite.
If able, take a clear photo of the snake from a safe distance — identification helps but is not essential (most UK snakes are non-venomous; only the adder bites humans/pets venomously).
Keep the dog as calm and still as possible during transport.

Do NOT

Do not let the dog walk if at all avoidable.
Do not apply a tourniquet — this concentrates venom and damages tissue.
Do not try to suck out venom or cut the wound.
Do not give human painkillers (paracetamol, ibuprofen) — both dangerous in dogs.
Do not waste time trying to catch or kill the snake — UK adders are protected by law and identification is rarely needed.

While transporting to the vet

Lay the dog on the back seat or boot floor with the bite area uppermost where possible.
Cool the bite gently with a damp cloth — do not apply ice directly.
Phone ahead so antivenom and pain relief are ready.
Note the location of the bite (muzzle, leg) and how it has changed since.

When to phone the vet immediately

Any suspected adder bite is an emergency
Rapid swelling, pale gums, collapse or vomiting
Bites to the muzzle or throat — airway swelling risk
Small dog or puppy — body weight magnifies venom dose

Common causes

Walks on heathland, moorland, sand dunes, or rocky south-facing slopes April–October
Dogs nosing into long grass or heather where adders bask
Encounters more common in spring (just out of hibernation) and warm summer days
UK regions: most of England, Wales and Scotland; absent from Ireland

What the vet will need to know

Time and location of the walk and bite
Site of bite and how rapidly it has swelled
Photo of the snake if safely obtainable
Dog's weight
Any current medications
Vomiting, weakness, or collapse

Aftercare

Treatment includes IV fluids, pain relief, antihistamines and often antivenom.
Hospitalisation typically 24–72 hours.
Bite-site swelling and bruising can take 1–2 weeks to fully resolve.
Watch for delayed kidney injury and clotting issues — repeat bloods at 48–72 hours.

Prevention

Stick to paths in known adder areas in spring and summer.
Keep dogs on lead in heathland April–October.
Learn the regional hotspots (Surrey heaths, New Forest, Peak District moorland, Welsh hillsides, Scottish moors).
Avoid letting dogs nose into long grass, heather, or rock crevices on warm days.
Carry the local emergency vet number when walking in remote rural areas.

Breed-specific notes

Small dogs are at higher risk of severe systemic effects from a given bite due to body weight.
Curious and prey-driven breeds (Terriers, Spaniels) are more likely to be bitten through nose-into-undergrowth behaviour.

Frequently asked questions

How do I know it was an adder and not a grass snake?

Adders have a clear zigzag pattern down the back and a V or X mark behind the head. Grass snakes are longer, plain green-brown with a yellow collar, and not venomous to dogs in any meaningful way. If in doubt, treat as adder and go to the vet.

Will my dog definitely need antivenom?

Not always — many bites are managed with fluids, pain relief and antihistamines. Antivenom is reserved for severe envenomation (rapid swelling, systemic signs, small dogs) and is held by larger or referral practices. The vet will decide based on signs and progression.

What time of year are adder bites most common?

April–October, with peaks in late spring as snakes emerge from hibernation and on warm summer afternoons when they bask. Bites are very rare in winter.